Ice makers are generally located in a freezer compartment or unit. The ice maker generally receives liquid water, waits an appropriate amount of time for the water to freeze and form ice cubes, and discharges the ice cubes into an ice tray or bucket. The ice cubes generally fall from the ice maker into the bucket which is also located in the freezer unit.
Prior art ice makers generally rely on a clock motor coupled with a cam mechanism or other electro-mechanical device to control the process of making ice cubes. For example, the clock motor and cam mechanism operate to control the reception of water and dumping of the ice cubes into the bucket. The cam mechanism may include adjustments for setting harvest rates for the ice cubes. Sophisticated ice makers may employ heating elements in the ice maker. The heating elements heat the just formed ice cubes just before they are discharged to the bucket so that the just formed ice cubes are easily extracted from the ice maker.
Ice makers also include a mechanical sensor which determines the level of ice cubes in the bucket. The mechanical sensor is configured to turn off the ice cube maker when a predetermined level of ice cubes in the bucket is reached so that the ice cubes do not overflow and spill out of the bucket. The mechanical sensor may turn off the ice cube maker by engaging a mechanical switch or the cam mechanism so that ice cubes are no longer produced by the ice maker.
The mechanical sensor generally includes a sense wire or bar and mechanical linkage. The mechanical linkage couples the sense wire to the ice maker, the cam mechanism, or other components which can turn the ice maker off. The sense wire is positioned inside the bucket at a predetermined level. At the start of each ice cube harvest cycle, the mechanical sense wire is forced up. The ice cubes are harvested and drop into the bucket. The mechanical sense wire is then lowered. When the level of ice cubes reaches the predetermined level, the ice cubes force the sense wire to remain in the up position. The moving of the sense wire is transmitted through the mechanical linkage to the ice maker. Generally, the mechanical linkage disables the cam mechanism so that the ice maker does not discharge ice cubes.
Mechanical sensors or touch sensors are often unreliable. The mechanical linkage and sense wire are susceptible to being jammed by ice cubes or other materials in the freezer unit. When the mechanical sensor is jammed, the movement of the sense wire and the mechanical linkage is obstructed so that the appropriate ice level cannot be sensed. Another problem is that ice cubes can impact the sense wire on their way into the bucket and deflect to another location outside the bucket. Also, freezer units which are consistently opened and closed are susceptible to frost build-up from the higher humidity in the room temperature or atmospheric air. The frost build-up often obstructs the movement of the sense wire and mechanical linkage.
Another disadvantage of mechanical sensors is that the sense wire and mechanical linkage must be mechanically calibrated to the predetermined level. Once the sense wire and mechanical linkage are set, they are often bumped, bent or otherwise accidentally adjusted as ice and other materials are stored and removed. Further, the bucket often bumps the sense wire and linkage as it is removed from the freezer unit.
Additionally, mechanical sensors are disadvantageous because they are bulky. The sense wire and mechanical linkage often obstruct the removal of the ice bucket from the freezer unit. The bucket must be carefully removed to avoid jarring the sense wire which is disposed within the bucket. Also, the sense wire and mechanical linkage require space which could be utilized for other components or items in the freezer unit.
Mechanical sensors are also disadvantageous because they are not easily replaceable. The sensor must be bolted to the freezer unit so that the sense wire is disposed within the bucket, and mechanically integrated with the existing linkage or ice maker for proper installation. This integration requires the sense wire or mechanical linkage to be mechanically coupled to the cam mechanism. These mechanical tasks make retrofitting existing ice makers with mechanical sensors very difficult and expensive.
Thus, there is a need for an ice level sensor which is not susceptible to jamming, does not obstruct the removal of the ice bucket, is easily calibrated, and can be easily installed in existing freezer units. More particularly, there is a need for a non-contact sensor for use with an ice maker which is not susceptible to the problems associated with prior art mechanical sensors.